1. A 0.321-g sample of aluminum is reacted with 1.000 g of solid sulfur to produce a specific
aluminum-sulfide compound. After the reaction, all of the aluminum is used and the mass of
un-reacted sulfur is 0.430 g. What is the mass of the compound produced?
2. A 0.847 g sample of nickel reacts with chlorine producing 1.870 g nickel(II) chloride as the
only product. Using the law of constant composition, determine the mass of nickel contained in
a 5.054 g sample of nickel(II) chloride.
3. The element “X” forms two compounds with element “Y”. In the first compound, 1.000 g X is
combined with 0.406 g Y. In the second compound, 2.000 g X reacts with 1.218 g Y. Show
that these results are consistent with Dalton’s law of multiple proportions.
4. For the following isotopes, write their symbols in the form
€
Z
AE
a. arsenic-75
b. gold-197
5. Indicate the number of protons, neutrons, and electrons in each of the following atoms:
a. tin-119
b. calcium-40
6. Indicate the number of protons, neutrons, and electrons in each of the following atoms:
a. 131Xe
b. 93Nb
7. Indicate the number of protons, neutrons, and electrons in each of the following ions:
a. 56Fe3+
b. 133Cs1+
8. Indicate the number of protons, neutrons, and electrons in each of the following ions:
a. 80Br –
b. 32S2–
9. The masses and percent abundances of the four un-naturally occurring isotopes of the
imaginary element notrealium are 71Nt, 70.2737 u, 17.054%; 73Nt, 72.2532 u, 24.531%; 77Nt,
76.2123 u, 13.067%; and 74Nt, 73.2430 u, 45.348%. Calculate the weighted-average atomic
mass of notrealium in atomic mass units, u.
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